nǐ fāshāo le, gǎnjǐn qù yīyuàn ba.

Not exactly. In this sentence, 了 does not simply mean past tense.

In 你发烧了, 了 often marks a new situation or change of state:

• before: you were not in the state of having a fever
• now: you are in that state

So 你发烧了 is more like:

• You’ve got a fever
• You have a fever now
• You came down with a fever

Mandarin does not have tense in the same way English does, so 了 is not just a past marker.

吧 softens the sentence and makes it sound like a suggestion, recommendation, or gentle urging.

So:

• 去医院。 = Go to the hospital.
  This sounds direct and blunt.
• 去医院吧。 = You’d better go to the hospital / Go to the hospital, okay?
  This sounds more natural and less harsh.

In this sentence, 吧 fits because the speaker is advising the other person.

赶紧 means quickly, at once, without delay, or hurry and...

It adds a sense of urgency:

• 赶紧去医院吧 = Hurry up and go to the hospital / You should go to the hospital right away

It is commonly used when the speaker feels something should be done immediately.

Yes, 你赶紧去医院吧 is absolutely possible.

In Chinese, once the subject is already clear, it is often omitted in the next clause. So:

• 你发烧了，赶紧去医院吧。
• 你发烧了，你赶紧去医院吧。

Both are grammatical. The version without the second 你 sounds more natural and less repetitive in many contexts.

In this sentence, 发烧 functions like a verb meaning to have a fever or to run a fever.

Examples:

• 我发烧了。 = I have a fever.
• 他昨天发烧了。 = He had/got a fever yesterday.

Unlike English, Mandarin often expresses illnesses with verb-like expressions rather than using to be:

• 我发烧了, not usually 我是发烧

So it is best to learn 发烧 as a chunk meaning to have a fever.

Because 发烧 is not normally linked with 是.

In Mandarin, 是 is mainly used to connect nouns:

• 我是老师。 = I am a teacher.

But for conditions, feelings, and many physical states, Chinese usually does not use 是:

• 我很累。 = I am tired.
• 他病了。 = He is sick.
• 你发烧了。 = You have a fever.

So 你是发烧了 would usually sound unnatural in normal speech.

It depends on context, but in ordinary conversation 你发烧了 usually means the fever is a current situation or something that has just happened.

Because 了 marks a new state, the most natural understanding is:

• You’ve got a fever
• You have a fever now

If you specifically want to talk about a past fever that is no longer relevant, you would normally add more context, such as time words or other information.

The sentence can be understood as two parts:

1. 你发烧了
   = You have a fever / You’ve come down with a fever

2. 赶紧去医院吧
   = Hurry and go to the hospital

So the whole sentence is:

[statement about the situation] + [advice/suggestion]

This is a very common pattern in Chinese:

• 你太累了，早点休息吧。
• 外面下雨了，带伞吧。

It is two closely connected clauses in one sentence.

The first clause states the reason or situation:

• 你发烧了

The second clause gives advice based on that situation:

• 赶紧去医院吧

Chinese often links ideas this way with a comma, especially in speech-like writing. In English, you might split it into two sentences:

• You have a fever. Go to the hospital right away.

But in Chinese, combining them with a comma is very normal.

Yes. Chinese does not have articles like a, an, and the.

So 去医院 can mean:

• go to a hospital
• go to the hospital

The exact meaning depends on context. In this sentence, English usually uses the hospital, but Chinese simply says 医院.

Because 去医院 is already complete and natural.

When going to a place, Chinese usually says:

• 去学校 = go to school
• 去公司 = go to the company/office
• 去医院 = go to the hospital

Adding 里 is possible in some contexts, but here it is unnecessary. 去医院里 would sound less natural for this basic meaning.

It sounds concerned and natural, not rude.

Why?

• 赶紧 adds urgency
• 吧 softens the advice

So the tone is something like:

• You have a fever — you should get to the hospital right away.

Without 吧, it would sound more forceful:

• 你发烧了，赶紧去医院。

With 吧, it feels more like caring advice.

Yes. 快 and 赶紧 can both express urgency, but they are slightly different.

• 快去医院吧 = Go to the hospital quickly / Hurry to the hospital
• 赶紧去医院吧 = Hurry up and go to the hospital right away

赶紧 often feels a bit more like don’t delay.
快 is simpler and very common too.

Both are natural.

The dictionary tones are:

• 发 = fā (1st tone)
• 烧 = shāo (1st tone)
• 了 = le (neutral tone here)

So it is pronounced:

• fāshāo le

There is no special tone change here. Just remember that 了 is light and unstressed.

Not directly in the same structure.

• 去医院 = go to the hospital
• 去看医生 = go see a doctor

So if you want to use 医生, you would usually say:

• 你发烧了，赶紧去看医生吧。

That is also very natural and often sounds even more everyday than 去医院吧, depending on the situation.